The present invention relates to the field of ophthalmic microscopy and photography, and more particularly to instruments for imaging structures located in the interior of the eye. Such imaging poses a number of technical problems. The eye is filled with vitreous humor, a fluid which may have differing clarity or scattering properties, depending on the patient's health and the illumination wavelengths employed, and all illumination or observation of interior structures relies on one or more optical paths passing through a small region, i.e., the iris. These factors limit the quality of attainable images, and in particular limit the attainment of high contrast. Other complicating factors include aberrations introduced by the curved eye geometry, and interfering reflections from eye tissue, particularly from the retina. Such factors affect both the quality of the image and the area over which acceptable imaging can be performed.
For imaging the fundus, many of these problems have been addressed by recently-developed scanning laser microscopes which illuminate a small area at any given instant, thus allowing very precise control of the illuminating and observation paths, and permitting reduction of scattered light by different combinations of path separation or spatial or temporal filtering of the collected light to enhance a scanned image.
In addition, various special techniques are used for observing different particular tissues in the eye. However, observation of the vitreous humor has remained problematic, for all of the reasons noted above, and further because the humor itself is a shifting fluid of low inherent visibility or reflectance compared to the background scattering and reflectances.